Nitron/Eibach suspension

[Gazza]

Cheers Bob,

I'm hoping to make it tuesday.

Gazza

[Monty]

Nice work guys

Glad to hear that the adjustment is on top of the damper as the AVO`s are lower down and are prone to seizing


BTW, i`d like my setup to be calculated so the car sits one inch lower than stock

[abmunro]

I'd like my set up the same as Monty's.

I can blame him if my rides crap...

[rip]

I think a few of us may get a chance to test the car on Tuesday.

Snow permitting, yes. It would seem like a good opportunity for others to try it out.

[bobbrown]

For the track day cars we are looking at some thing around the 450 to 500 lb/inch front springs and rears and dampers to match this is not an insignificant increase and is close to double the standard rate on the front but it does tend to fall in line with what is done to the Elise for track days all be it the Elise is lighter and the weight distribution is different. It my well be that the spring rates need to go even higher and it will have an impact on the "comfort" but the increase in the road car’s springs does not seem to have made the car less comfortable.
As for lowering the cars this is possible but it will require the suspension geometry is checked.

The big advantage the Nitron system has over any of the others is it is customisable so you can have a road, track or full race setup if you wish.

[chris.t]

Bob, for my information what exactly happens during the testing procedure ie what do they do, is it all subjective? For my final setup I want the car to be what I call 'fast road' which basically is half way between track and road. I will get the geometry done to suit. I would also like the car lowered too. Is it possible to relay my personal requirements to Nitron so that my wishes can be realised? My VX has a fairly firm ride so sacrificing some of the ride comfort is not a great concern of mine - don't tell Dee that though

[rip]

Hi Chris,

I may be able to answer some of your questions.

Bob had some reliable data, then he & the guys at Nitron did some calculations to find the spring rates & damper settings.
Owing to the issues we had when fitting the new suspension, we had no time for testing & re-adjustment. The car felt good on the way home though & I will be taking it on some familiar bumpy & twisty roads on Tuesday to get a better feel for the new setup.

It is definitely possible to lower your Elan. Nitron were keen to lower mine but I was a bit hesitant about this & Bob advised them against it. The dampers are adjustable, so I could lower it myself if I wished. Nitron have even supplied me with an adjustment tool, but a 6mm drill bit will be sufficient.

If you need a reference point, you are welcome to test drive my Elan.

[bobbrown]

Sorry, just a slight correction rip.
The helper springs were fitted to get the ride height correct as the springs on the rear have only a small amount of pre load in the original setup up going to stiffer springs meant that the spring seats had to be too low to get the correct ride height.
The rear of the car has two spring rates a slightly lower one until the helper spring is fully compressed and it gets a little complicated as the formula for two springs is s1*s2/s1+s2 when the two springs are working together but once the helper has gone coil bound it is just the main spring. So say a 150 lb/in and a 200 lb/in spring gives about the equivalent of a 85 lb/in spring until the transition point is reach when it returns to 200.

Lotus Elan Fast Road Rear.jpg (24.25 KiB) Viewed 5153 times

To get this to work with a single spring the damper will need to be shorter and I am going to discuss this with Pete on Monday as there are some small details I need to iron out.

I have to have a very close look into the best way to lower the car as there are some issues with clearance to the wheel arch liner and bump travel that need to be addressed not say it can not be done but it may mean using a damper that is 15mm shorter and a helper spring to get to the ride height required plus the geometry will need to be reset for this new ride height and as Monty has said it does tend to go out of the adjustment range. It may need a compromise and only lower the car by 15 to 20mm.
If you wanted to go really hardcore for a track only car then the suspension travel is not so much of an issue but with our public roads................

Bob

off to make a K series engine to a Midget go Brummmmmmmmmm

[chris.t]

Iain, thanks very much for the offer which if i can I will take you up on. What would clinch it for me though is to run the car on track then I would definitely be able to know what was what. After driving Paul and Nobby's cars on track on the IOM I now know how out of shape the suspension on my car is. Money no object i would like to get the Nitron guys to fit their best guess for the suspension and then run the car up to Silverstone/Bedford to try it out, with follow up tweaks. Maybe this could be possible???

[bobbrown]

Chris
Have you considered Abingdon Airfield? If I have it right only 15 miles from Witney
As I assume you know how the car handles at present so drive up to Witney the day before, get the suspension sorted and then test the following day. Cheap enough trackday at £120.00 ish

Bob

[Nohair]

Are these new dampers likely to have an effect on body roll...my car seems to lean over on its door handles
NH

[Monty]

Bob makes a good point on lowering, I`ve lowered Pinky II by approx one inch and i have had slight rubbing on the wheel arch liners when on track, in fact the near side has worn through (but good old duct tape comes in handy). The other problem is speed humps, the one piece speed humps are ok if taken at 20mph but the double speed humps are a pain as they catch my Exhuast (Peco) i have to go through the middle of the two or if vechiles are coming in the other direction i slow right down and let the right wheels drive over the single speed bump.

Another problem is that i have bottomed out on the bumpy country lanes i`ve even been told that the car has bottom out on at deers leap at oulton park but i assume with the stiffer set up the car won`t compress as much.

Saying all that i`m quite happy having Pinky sitting 1" lower

[bobbrown]

Are these new dampers likely to have an effect on body roll...my car seems to lean over on its door handles
NH

It is not so much the dampers that effect body roll but the springs, the dampers will slow down the rate at which the body rolls but not stop the roll it is the springs and anti roll bars that control roll.
If you have a lot of roll I would check the anti roll bar fixings as these have been known to fail where they join the wish bone and they are not very strong as Rip can testify


Bob

[bobbrown]

Bob makes a good point on lowering, I`ve lowered Pinky II by approx one inch and i have had slight rubbing on the wheel arch liners when on track, in fact the near side has worn through (but good old duct tape comes in handy). The other problem is speed humps, the one piece speed humps are ok if taken at 20mph but the double speed humps are a pain as they catch my Exhuast (Peco) i have to go through the middle of the two or if vechiles are coming in the other direction i slow right down and let the right wheels drive over the single speed bump.

Another problem is that i have bottomed out on the bumpy country lanes i`ve even been told that the car has bottom out on at deers leap at oulton park but i assume with the stiffer set up the car won`t compress as much.

Saying all that i`m quite happy having Pinky sitting 1" lower

If the damper lengths and travel are the same as standard then there is no reason the wheels should hit the wheel arch liner even with the bump stop removed but if there is more travel or the dampers are shorter then there is a chance the wheels could hit the liner. I have a suspicion that the current aftermarket offerings have not been checked to ensure they do not foul on full bump with no bump stops.
The only way to check this is to either measure every thing up or remove the spring and bump stop and wind the wheel up into the arch, the amount of travel with standard front dampers and no bump stop is about 4" so the wheel travel is around the 7" due to the motion ratio. If the current aftermarket offerings have a travel of say 4.5" then this means the wheel travel is increased by 1" and all other things being equal then the wheels will almost certainly hit the liner as there is not a lot of room to play with. Nitron have kept the travel the same as the original at 4" and on the road setup the length is the same which means that the wheels should not hit the liner.
I have been looking into this and it is quite tight, I think there is room to get the car down the 1" people have asked for but it will mean reducing the wheel travel, probably by 1" and still retain clearance to the wheel arch liner this should be no problem on track but as some will know race cars require a smaller amount of wheel travel than a forest rally car due to the surface they are running on.

If anyone happens to have one of the aftermarket offerings fitted and happen to jack the car up could they measure the free length of the damper as that will give the game away.

Bob

[rip]

If you have a lot of roll I would check the anti roll bar fixings as these have been known to fail where they join the wish bone and they are not very strong as Rip can testify

Bob

Yep. One of mine broke when Nitron tried to dismantle the assembly to get the old suspension off. One side came off ok, but the other broke. It wasn't their fault: it had simply failed due to corrosion.
Fortunately, Bob was there to engineer a stronger solution on the fly. It involved purchasing some parts from an engineering company though.

[rip]

we had another issue with the car outside of the suspension which I will let rip explain if he so wishes.

Yes, when a jacking point started to give way.

It has nothing to do with the suspension upgrade though, but I have just foundthis thread which I think is well worth a read.

[bobbrown]

For the owners of USA spec cars, Elanlover has been kind enough to measure the dampers and springs off his car.
I have worked out where we need to go with the Fed cars assuming the ride height remains the same.
It looks like all Lotus did was change the spring rates with dampers to suit all be it dimensionally the same or if not very very close, to raise the car the required amount to meet USA regulations in force at the time. So to this end all that is required for a Fed spec is to increase the spring rates and if needed change the damper rates to suit.

Bob

[Elanlover]

Bob, could it be that lotus changed the mounting points at all? As in raised them somehow so the car would sit a bit higher? Perhaps a spacer or something? I've no idea how we'd check that or if its even a reasonable suggestion at all. I'm just grasping at straws really as I can't quite picture how changing the spring rates would raise the car up. Could you explain how that might work - for the uninitiated of course.

[bobbrown]

Bob, could it be that lotus changed the mounting points at all? As in raised them somehow so the car would sit a bit higher? Perhaps a spacer or something? I've no idea how we'd check that or if its even a reasonable suggestion at all. I'm just grasping at straws really as I can't quite picture how changing the spring rates would raise the car up. Could you explain how that might work - for the uninitiated of course.

Quite simple really.

If the front had say 250 lb/inch springs and the load on the spring was say 750lbs then the spring would compress 3" if you substitute the 250lb spring for one of say 300lb/inch then the spring only compresses 2.5" for the same load.
So in the case of the car every thing else being equal the car with high rate springs will run with a raised ride height.
I have heard 1" mentioned but I do not think that this is the case with the fed cars as it would require more than just stronger springs as to get to 1" with just springs. From your figures I do not thing this is the case as the wire diameter of the springs is only 13.3mm uk and 13.75 diameter Fed, might not seem much but it does increase the spring rate by quite a bit as it goes up by the fourth power of the material diameter.
There is a small increase in sprung weight on the front of the Fed Elan but it is only small when you break it down to each corner around 30lbs on the front and in fact due to the added weight mainly in the crash structure at the front it actually decrease the weight at the rear. This extra weight on the Fed car would only lower the front around 1/10" if the car was on 300lb/inch springs
I've yet to see anything concrete with regard to ride heights for the Fed cars so if any one has any figures it would be useful.

[Elanlover]

Ahh..........I get it now! Thanks for the simple explanation!

Also, I have a Fed manual at home. I'l check tonight to see if they mention anything specific about the Fed ride height.